Method for Handover Between Access Points, and Terminal Equipment

ABSTRACT

The present invention provides a method for handover between access points, and terminal equipment. The method includes: when performing information transmission with a first access point AP on a first frequency band, determining whether the terminal equipment needs to establish a connection with a second AP which is a second frequency band; determining, by the terminal equipment, whether the first AP and the second AP are corresponding to a same dual-band radio access device; sending, by the terminal equipment, a connection request to the second AP when maintaining a protocol layer connection with the first AP; and establishing, by the terminal equipment, the connection with the second AP when the second AP send feedback. In the method, duration required by a process of handover between access points can be reduced, and a user is made not perceive the handover process, thereby improving user experience.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage of International Application No.PCT/CN2016/084136, filed on May 31, 2016, which application is herebyincorporated herein by reference.

TECHNICAL FIELD

Embodiments of the present invention relate to the communications field,and more specifically, to a method for handover between access points,and terminal equipment.

BACKGROUND

A Wireless Fidelity (“WiFi” for short) technology is a generic term fortechnologies that are based on the IEEE 802.11 protocol family andsupport local area wireless network communication. A system mainlyincludes a client (Station, “STA” for short) and an access point (“AP”for short). The STA and the AP perform communication by using an airinterface, that is, by means of wireless transmission. The AP connectsthe STA to a local area network of the Internet, so that the STA canaccess the Internet.

Currently, application of a dual-band AP is becoming increasinglypopular. The dual-band AP can simultaneously operate on 2.4G and 5Gfrequency bands. However, currently, most STAs do not support operatingon dual bands. That is, a STA cannot simultaneously operate on the 2.4Gand 5G frequency bands. For example, once accessing a 2.4G AP, the STAcan operate only on the 2.4G frequency band, and cannot use the 5Gfrequency band for data transmission. Therefore, a method for handoverbetween access points needs to be used to hand over the STA to an APthat exists in a desirable channel status.

An existing method for handover between access points includes firstdisconnecting a STA from a current AP and then connecting the STA to anew AP. Duration required by a handover process in this method isrelatively long, and a data service in use is interrupted, affectinguser experience. Therefore, a method for handover between access pointsneeds to be provided to reduce duration required by a handover processand improve user experience.

SUMMARY

This application provides a method for handover between access points,and terminal equipment, so as to reduce duration required by a handoverprocess, and make a user not perceive the handover process, therebyimproving user experience.

According to a first aspect, a method for handover between access pointsis provided, including: when terminal equipment performs informationtransmission with a first access point (“AP” for short) on a firstfrequency band, determining, by the terminal equipment, whether theterminal equipment needs to establish a connection with a second AP,where an operating frequency band of the second AP is a second frequencyband; when the terminal equipment determines that the terminal equipmentneeds to establish the connection with the second AP, determining, bythe terminal equipment, whether the first AP and the second AP arecorresponding to a same dual-band radio access device; when the terminalequipment determines that the first AP and the second AP arecorresponding to the same dual-band radio access device, sending, by theterminal equipment, a connection request to the second AP whenmaintaining a protocol layer connection with the first AP, where theconnection request is used to request to establish a connection with thesecond AP; and if the terminal equipment receives a success message thatis fed back according to the connection request and that is sent by thesecond AP, establishing, by the terminal equipment, the connection withthe second AP.

It can be understood that the protocol layer connection between theterminal equipment and the first AP is a Transmission Control Protocol(“TCP” for short)/Internet Protocol “IP” for short) connection betweenthe terminal equipment and the first AP. The first AP is an AP to whichthe terminal equipment is currently connected, and the first AP may bereferred to as an original AP. The second AP is an AP to which theterminal equipment is to be handed over, and the second AP may bereferred to as a target AP.

Therefore, in the method for handover between access points in thisapplication, when the terminal equipment determines that the original APand the target AP are corresponding to the same dual-band radio accessdevice, the terminal equipment may establish the connection with thetarget AP when maintaining the protocol layer connection with theoriginal AP. In this case, during a process of handing over terminalequipment to an access point, an IP connection of an upper-layerapplication of a user is not removed, so that the user does not perceivethe handover process. In addition, when the terminal equipmentestablishes the connection with the target AP, the target AP does notneed to assign an IP address to the terminal equipment, so as to reduceduration required by the handover process, thereby improving userexperience.

Optionally, when the terminal equipment determines that the terminalequipment needs to establish the connection with the second AP, theterminal equipment determines whether service set identifiers (“SSID”for short) and passwords of the first AP and the second AP are the same.When the terminal equipment determines that the SSIDs and/or thepasswords of the first AP and the second AP are different, the terminalequipment determines whether the first AP and the second AP share a sameDynamic Host Configuration Protocol (“DHCP” for short) server. When theterminal equipment determines that the first AP and the second AP sharethe same DHCP server, the terminal equipment sends a connection requestto the second AP when maintaining a TCP/IP connection with the first AP,where the connection request is used to request to establish aconnection with the second AP. If the terminal equipment receives asuccess message that is fed back according to the connection request andthat is sent by the second AP, the terminal equipment establishes theconnection with the second AP.

Therefore, even if the SSIDs and/or the passwords of the first AP andthe second AP are different, as long as the first AP and the second APshare the same DHCP server, the terminal equipment can establish theconnection with the target AP when maintaining the TCP/IP connectionwith the original AP. In this case, during a process of handing overterminal equipment to an access point, an IP connection of anupper-layer application of a user is not removed, so that the user doesnot perceive the handover process. In addition, when establishing theconnection with the target AP, the terminal equipment does not need tore-apply for an IP address from the second AP, so as to reduce durationrequired by the handover process, thereby improving user experience.

With reference to the first aspect, in a first possible implementationof the first aspect, the determining, by the terminal equipment, whetherthe first AP and the second AP are corresponding to a same dual-bandradio access device includes: determining, by the terminal equipmentaccording to a relationship between a basic service set identifier(“BSSID” for short) of the first AP and a BSSID of the second AP,whether the first AP and the second AP are corresponding to the samedual-band radio access device; or determining, by the terminal equipmentaccording to a relationship between a Media Access Control (“MAC” forshort) address of a default gateway of the first AP and a MAC address ofa default gateway of the second AP, whether the first AP and the secondAP are corresponding to the same dual-band radio access device.

With reference to the first aspect or the first possible implementationof the first aspect, in a second possible implementation of the firstaspect, the determining, by the terminal equipment, whether the terminalequipment needs to establish a connection with a second AP includes:scanning, by the terminal equipment, channels on the first frequencyband and the second frequency band; and determining, by the terminalequipment according to a result of scanning the channels on the firstfrequency band and the second frequency band, whether the terminalequipment needs to establish the connection with the second AP.

During a channel scanning process, the terminal equipment may obtainreceived signal strength indicators (“RSSI” for short) that arecorresponding to different APs, and the terminal equipment maydetermine, according to the RSSIs that are corresponding to thedifferent APs, whether handover between access points is required.

With reference to the second possible implementation of the firstaspect, in a third possible implementation of the first aspect, thescanning, by the terminal equipment, channels on the first frequencyband and the second frequency band includes: scanning, by the terminalequipment, any channel of the channels on the first frequency band andthe second frequency band; when the terminal equipment completesscanning of the any channel, determining, by the terminal equipment,whether there is to-be-sent data; when the terminal equipment determinesthat there is to-be-sent data, sending, by the terminal equipment, theto-be-sent data by using the first frequency band; and after theterminal equipment sends the to-be-sent data by using the firstfrequency band, continuing scanning, by the terminal equipment, anotherchannel of the channels on the first frequency band and the secondfrequency band.

In other words, the terminal equipment may perform channel scanning in abackground scanning manner. This can ensure that during a channelscanning process, the terminal equipment and the original AP can performdata exchange without causing stream interruption on the terminalequipment. Therefore, user experience can be improved.

With reference to the second or the third possible implementation of thefirst aspect, in a fourth possible implementation of the first aspect,the method further includes: determining, by the terminal equipment, afirst channel and a second channel, where the first channel is anoperating channel of the first AP on the first frequency band, and thesecond channel is an operating channel of the second AP on the secondfrequency band; and the scanning, by the terminal equipment, channels onthe first frequency band and the second frequency band includes:scanning, by the terminal equipment, the first channel and the secondchannel.

In other words, when performing channel scanning, the terminal equipmentmay scan only operating channels of the original AP and the target AP,and determine, according to a result of scanning the operating channelsof the original AP and the target AP, whether handover between accesspoints is required.

Therefore, the terminal equipment needs to scan only two channelsinstead of scanning all channels, so that time overheads of channelscanning can be reduced, thereby reducing time required by a handoverprocess and improving user experience.

With reference to the fourth possible implementation of the firstaspect, in a fifth possible implementation of the first aspect, beforethe determining, by the terminal equipment, whether the terminalequipment needs to establish a connection with a second AP, the methodfurther includes: storing, by the terminal equipment, a first networkconfiguration of the first AP and a second network configuration of thesecond AP, where the first network configuration includes the firstchannel, and the second network configuration includes the secondchannel; and the determining, by the terminal equipment, a first channeland a second channel includes: determining, by the terminal equipment,the first channel according to the first network configuration; anddetermining, by the terminal equipment, the second channel according tothe second network configuration.

Optionally, when the terminal equipment previously establishesconnections with the first AP and the second AP, the terminal equipmentstores a network configuration of the first AP and a networkconfiguration of the second AP, where the network configuration of thefirst AP may also include the SSID and/or the password of the first APin addition to the operating channel of the first AP, and the networkconfiguration of the second AP may also include the SSID and/or thepassword of the second AP in addition to the operating channel of thesecond AP. By querying the stored network configurations, the terminalequipment can learn the operating channels of the first AP and thesecond AP in advance, so that scanning is performed only on theoperating channels of the first AP and the second AP during channelscanning. Therefore, time overheads of scanning can be reduced.

With reference to any one of the first aspect or the first to the fifthpossible implementations of the first aspect, in a sixth possibleimplementation of the first aspect, the sending a connection request tothe second AP includes: sending a reassociation request frame to thesecond AP, where the reassociation request frame carries the BSSID ofthe first AP.

Therefore, on a network, a data packet sent to the original AP can beforwarded to the target AP, so as to reduce a packet loss during ahandover process.

With reference to any one of the first aspect or the first to the sixthpossible implementations of the first aspect, in a seventh possibleimplementation of the first aspect, the first frequency band is 2.4 GHz,and the second frequency band is 5 GHz; or the first frequency band is 5GHz, and the second frequency band is 2.4 GHz.

According to a second aspect, terminal equipment is provided, where theterminal equipment is configured to execute the method in the foregoingfirst aspect or any possible implementation of the first aspect.Specifically, the terminal equipment includes units configured toexecute the method in the foregoing first aspect or any possibleimplementation of the first aspect.

According to a third aspect, terminal equipment is provided, including aprocessor, a memory, and a transceiver, where the processor, the memory,and the transceiver are connected by using a bus system, the memory isconfigured to store an instruction, the transceiver receives and sends amessage under control of the processor, to implement communicationbetween the terminal equipment and an AP, and the processor isconfigured to invoke the instruction stored in the memory, to executethe method in the foregoing first aspect or any possible implementationof the first aspect.

According to a fourth aspect, a computer readable medium is provided,where the computer readable medium is configured to store a computerprogram, and the computer program includes an instruction used toexecute the method in the first aspect or any possible implementation ofthe first aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention more clearly, the following briefly introduces theaccompanying drawings required for describing the embodiments of thepresent invention. Apparently, the accompanying drawings in thefollowing description show merely some embodiments of the presentinvention, and a person of ordinary skill in the art may still deriveother drawings from these accompanying drawings without creativeefforts.

FIG. 1 is a schematic diagram of an application scenario according to anembodiment of the present invention;

FIG. 2 is a schematic flowchart of a method for handover between accesspoints according to an embodiment of the present invention;

FIG. 3 is a schematic flowchart of a method for handover between accesspoints according to another embodiment of the present invention;

FIG. 4 is a schematic block diagram of terminal equipment according toan embodiment of the present invention; and

FIG. 5 is a schematic block diagram of terminal equipment according toanother embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of the present invention with reference to the accompanyingdrawings in the embodiments of the present invention. Apparently, thedescribed embodiments are a part rather than all of the embodiments ofthe present invention. All other embodiments obtained by a person ofordinary skill in the art based on the embodiments of the presentinvention without creative efforts shall fall within the protectionscope of the present invention.

In the embodiments of the present invention, terminal equipment may alsobe referred to as user equipment (“UE” for short), a mobile station(“MS” for short), a mobile terminal, a client (“STA” for short), or thelike. The terminal equipment may communicate with one or more corenetworks by using a radio access network (“RAN” for short). For example,the terminal equipment may be a mobile phone (or referred to as a“cellular” phone), a computer with a mobile terminal, or the like. Forexample, the terminal equipment may be a portable, pocket-sized,handheld, computer built-in, or in-vehicle mobile apparatus, terminalequipment in a future 5G network, terminal equipment in a future evolvedPLMN network, or the like.

In the embodiments of the present invention, a radio access device is adevice with a wireless-to-wired bridging function. A dual-band radioaccess device is a radio access device that can simultaneously operateon two frequency bands. A current dual-band radio access device cansimultaneously operate on a 2.4 GHz frequency band and a 5 GHz frequencyband. An access point (“AP” for short), commonly known as a “hotspot”,is a workstation that has a basic service set (“BSS” for short) functionof managing an infrastructure and that makes terminal equipment access adistributed system. One dual-band radio access device can provide twoAPs. For example, a dual-band radio access device that simultaneouslyoperates on the 2.4 GHz frequency band and the 5 GHz frequency band canprovide a 2.4 GHz AP and a 5 GHz AP.

FIG. 1 is a schematic diagram of an application scenario according to anembodiment of the present invention. As shown in FIG. 1, a dual-bandradio access device can simultaneously operate on a 2.4 GHz frequencyband and a 5 GHz frequency band. It can be understood that a 5 GHzsignal has advantages of a wide frequency band, low interference, and ahigh throughput rate. However, a 5 GHz channel has a poorwall-penetration capability. By contrast, a 2.4 GHz signal has aslightly narrow frequency band but has a desirable wall-penetrationcapability and a wide coverage area.

As a distance between terminal equipment and the dual-band radio accessdevice changes, a frequency band occupied when the terminal equipmentand the dual-band radio access device perform information transmissionneeds to change (it can also be understood that an AP accessed by theterminal equipment changes). As shown in FIG. 1, when the terminalequipment is nearer the dual-band radio access device (for example,within 10 meters), the terminal equipment selects the 5 GHz frequencyband (accesses a 5 GHz AP) to perform information transmission with thedual-band radio access device. This can improve a throughput rate underthe premise of ensuring communication quality. When the terminalequipment is farther away from the dual-band radio access device (forexample, between 10 meters and 100 meters), channel quality graduallybecomes deteriorated, and the terminal equipment chooses to be handedover to the 2.4 GHz frequency band (accesses a 2.4 GHz AP) to performinformation transmission with the dual-band radio access device, therebyensuring long-distance coverage of a signal.

On this basis, a method for handover between access points may beprovided. Smooth and seamless switching from an original AP to a targetAP can be implemented as long as the original AP and the target AP arecorresponding to the same dual-band radio access device, so as to avoida waste of network resources and improve user experience.

The following uses an example in which an encryption manner of awireless network is Wireless Fidelity Protected Access (“WAP” for short)or WAP2 to describe a method for handover between access points in theembodiments of the present invention. It can be understood that themethod for handover between access points in the embodiments of thepresent invention can also be applied to a scenario in which anotherencryption manner is used for encryption of a wireless network or awireless network is not encrypted, for example, a scenario in which awired equivalent privacy (“WEP” for short) manner or an open manner isused for encryption of the wireless network.

It should be noted that, when a specific embodiment is described,“first” and “second” are used merely for distinguishing betweendescribed objects and do not constitute any limitation on the describedobjects.

FIG. 2 is a schematic flowchart of a method for handover between accesspoints according to an embodiment of the present invention. As shown inFIG. 2, a method 1000 includes the following steps.

S1100: When terminal equipment performs information transmission with afirst access point AP on a first frequency band, the terminal equipmentdetermines whether the terminal equipment needs to establish aconnection with a second AP, where an operating frequency band of thesecond AP is a second frequency band.

It can be understood that, that the terminal equipment performsinformation transmission with the first AP on the first frequency bandindicates that the first frequency band is an operating frequency bandof the first AP.

Optionally, for example, when the terminal equipment performsinformation transmission with the first AP on the first frequency band,the terminal equipment scans channels on the first frequency band andthe second frequency band. Each operating frequency band iscorresponding to one or more channels. The terminal equipmentdetermines, according to a channel scanning result, whether the terminalequipment needs to establish the connection with the second AP. Forexample, the first frequency band is 2.4 GHz, and the second frequencyband is 5 GHz; or the first frequency band is 5 GHz, and the secondfrequency band is 2.4 GHz. The 2.4 GHz frequency band is correspondingto 13 channels, and the 5 GHz frequency band is corresponding to fivechannels.

Specifically, during a process in which the terminal equipment performschannel scanning, the terminal equipment may obtain information about anAP that is around the terminal equipment. The information about the APincludes an SSID, a basic service set identifier (“BSSID” for short), anoperating channel, and a bandwidth of the AP, a received signal strengthindicator (“RSSI” for short) corresponding to the AP, and otherinformation. The terminal equipment determines, according to theinformation about the AP, whether handover between access points isrequired.

Optionally, for example, during channel scanning by the terminalequipment, the terminal equipment uses a background scanning manner toperform channel scanning. Specifically, the terminal equipment choosesto scan any channel on the first frequency band and the second frequencyband. After completing scanning of the channel, the terminal equipmentswitches to the operating channel of the first AP to detect whether theterminal equipment is to receive or to send data. If the terminalequipment is to send buffered data, the terminal equipment sends thebuffered data on the operating channel of the first AP, or if theterminal equipment is to receive data, the terminal equipment receivesthe to-be-received data on the operating channel of the first AP, andthen switches to a next channel for scanning. Therefore, it is ensuredthat stream interruption does not occur on the terminal equipment duringthe channel scanning process. During channel scanning, the terminalequipment may choose to scan all of the 13 channels on the 2.4 GHzfrequency band and the five channels on the 5 GHz frequency band.

Further, the terminal equipment may further determine the operatingchannel of the first AP and an operating channel of the second AP beforeperforming channel scanning, so that during channel scanning, theterminal equipment scans only two channels, that is, the operatingchannel of the first AP and the operating channel of the second AP. Thisreduces time consumed by channel scanning.

Optionally, when the terminal equipment previously establishesconnections with the first AP and the second AP, the terminal equipmentstores a network configuration of the first AP and a networkconfiguration of the second AP, where the network configuration of thefirst AP includes the operating channel of the first AP, and the networkconfiguration of the second AP includes the operating channel of thesecond AP. Therefore, only by querying the network configurations storedby the terminal equipment, the terminal equipment can determine theoperating channels of the first AP and the second AP.

Alternatively, the terminal equipment may receive a networkconfiguration of the first AP and a network configuration the second APby establishing device-to-device (“D2D” for short) communication withanother terminal equipment. The network configurations of the first APand the second AP are stored by the another terminal equipment when theanother terminal equipment establishes connections with the first AP andthe second AP, and are sent by the another terminal equipment.

Alternatively, the terminal equipment may receive, by performinginteraction with a cloud server, a network configuration of the first APand a network configuration of the second AP that are delivered by thecloud server.

It can be understood that the network configuration of the first AP mayalso include an SSID and/or a password of the first AP in addition tothe operating channel of the first AP, and the network configuration ofthe second AP may also include an SSID and/or a password of the secondAP in addition to the operating channel of the second AP.

S1200: When the terminal equipment determines that the terminalequipment needs to establish the connection with the second AP, theterminal equipment determines whether the first AP and the second AP arecorresponding to a same dual-band radio access device.

Specifically, the terminal equipment determines, according to arelationship between a BSSID of the first AP and a BSSID of the secondAP, whether the first AP and the second AP are corresponding to the samedual-band radio access device. When the first 16 bits of the BSSID ofthe first AP and the first 16 bits of the BSSID of the second AP are thesame, the terminal equipment determines that the first AP and the secondAP are corresponding to the same dual-band radio access device.Alternatively, the terminal equipment determines, according to arelationship between a Media Access Control (“MAC” for short) address ofa default gateway of the first AP and a MAC address of a default gatewayof the second AP, whether the first AP and the second AP arecorresponding to the same dual-band radio access device. If the MACaddress of the default gateway of the first AP and the MAC address ofthe default gateway of the second AP are the same, the terminalequipment determines that the first AP and the second AP arecorresponding to the same dual-band radio access device. A method fordetermining whether the first AP and the second AP are corresponding tothe same dual-band radio access device is not limited herein.

S1300: When the terminal equipment determines that the first AP and thesecond AP are corresponding to the same dual-band radio access device,the terminal equipment sends a connection request to the second AP whenmaintaining a protocol layer connection with the first AP, where theconnection request is used to request to establish a connection with thesecond AP.

The protocol layer connection between the terminal equipment and thefirst AP is a Transmission Control Protocol (“TCP” for short)/InternetProtocol (“IP” for short) connection between the terminal equipment andthe first AP.

S1400: If the terminal equipment receives a success message that is fedback according to the connection request and that is sent by the secondAP, the terminal equipment establishes the connection with the secondAP.

The terminal equipment sends the connection request to the second APwhen maintaining the TCP/IP connection with the first AP, indicatingthat the terminal equipment is disconnected from the first AP on aphysical channel, switches to the operating channel of the second AP tosend the connection request to the second AP, and establishes theconnection with the second AP when receiving positive feedback from thesecond AP on the operating channel of the second AP. In this case,during a process of handing over terminal equipment to an access point,the terminal equipment removes only a physical layer connection with thefirst AP, and does not remove the protocol layer connection with thefirst AP. Therefore, an upper-layer application service of a user is notterminated, and the user does not perceive the handover process, anduser experience is improved.

For example, assuming that a user is performing video communication withanother user by using WeChat, if the terminal equipment establishes theconnection with the second AP when maintaining the TCP/IP connectionwith the first AP, a user interface (“UI” for short) of the terminalequipment stalls for a short moment, but a video interface on the UI isnot automatically interrupted, and the user does not need to restart toinitiate a video connection. In this case, the user does not perceivethe handover process, and user experience is improved.

In addition, the terminal equipment maintains the TCP/IP connection withthe first AP, and the terminal equipment stores an IP address that isassigned by the first AP to the terminal equipment. Because the first APand the second AP are corresponding to the same dual-band radio accessdevice, the first AP and the second AP share a same Dynamic HostConfiguration Protocol (“DHCP” for short) server. Therefore, when theterminal equipment establishes the connection with the second AP, theterminal equipment does not need to apply for an IP address from thesecond AP, reducing time consumed by the handover process.

Optionally, for example, after establishing the connection with thesecond AP, the terminal equipment may release the TCP/IP connection withthe first AP. In this case, network resources can be saved.

FIG. 3 is a schematic flowchart of a method for handover between accesspoints according to a specific embodiment of the present invention. Asshown in FIG. 3, a method 2000 includes the following steps.

S2100: Terminal equipment sends a probe request frame and receives aprobe response frame sent by a second AP.

A first AP and the second AP in FIG. 3 are corresponding to a samedual-band radio access device. The terminal equipment currentlyestablishes a connection and performs communication with the first AP.The terminal equipment performs channel scanning by sending the ProbeRequest frame and receiving the Probe Response frame sent by the AP. Theterminal equipment may specifically use a manner in S1100 of the method1000 to perform channel scanning. To avoid repetition, details are notdescribed herein again.

The Probe Response frame includes information about the second AP. Theterminal equipment determines, according to the information about thesecond AP in the Probe Response frame, whether handover between accesspoints is required. For example, when the terminal equipment determines,according to the received Probe Response frame from the second AP, thatan RSSI value corresponding to the second AP is greater than an RSSIvalue corresponding to the first AP, the terminal equipment determinesthat the terminal equipment needs to establish a connection with thesecond AP. When the terminal equipment determines, according to thereceived Probe Response frame, that the RSSI value corresponding to thefirst AP is greater than an RSSI value corresponding to another AP, theterminal equipment determines that the terminal equipment does not needto be handed over to an access point but still maintains the connectionwith the first AP.

In S2100, the terminal equipment may send the Probe Request frame in abroadcast mode, or may send the Probe Request frame to the second AP ina unicast mode. This is not limited in this embodiment of the presentinvention.

Optionally, for example, in S2100, the terminal equipment may determine,by using the information about the second AP in a received beacon frame(Beacon) sent by the second AP, whether the terminal equipment needs toestablish the connection with the second AP. For example, the terminalequipment receives multiple Beacon frames, and each Beacon frame iscorresponding to one AP. If an RSSI value that is in a Beacon frame andthat is corresponding to the second AP is greater than an RSSI valuethat is in the Beacon frame and that is corresponding to another AP, theterminal equipment determines that the terminal equipment needs toestablish the connection with the second AP.

Specifically, a method in which the terminal equipment determines,according to the information about the second AP, whether handoverbetween access points is required is as follows:

First, the terminal equipment determines whether an SSID and a passwordof the first AP and an SSID and a password of the second AP are thesame, and whether the RSSI value corresponding to the second AP isgreater than the RSSI value corresponding to the first AP.

If the SSIDs and the passwords of the first AP and the second AP are thesame and the RSSI value corresponding to the second AP is greater thanthe RSSI value corresponding to the first AP, it indicates that thefirst AP and the second AP are two APs on a same local area network, anda roaming mechanism in the prior art can be directly started to handover the terminal equipment from the first AP to the second AP by meansof roaming.

If the RSSI value corresponding to the second AP is greater than theRSSI value corresponding to the first AP but the SSIDs and/or thepasswords of the first AP and the second AP are different, the terminalequipment further determines whether the first AP and the second AP arecorresponding to the same dual-band radio access device. For a methodfor determining whether the first AP and the second AP are correspondingto the same dual-band radio access device, reference may be made to theforegoing embodiment, and details are not described herein again.

If the terminal equipment determines that the first AP and the second APare corresponding to the same dual-band radio access device and that theRSSI value corresponding to the second AP is greater than the RSSI valuecorresponding to the first AP, step S2200 is performed.

S2200: The terminal equipment sends an authentication request(Authentication Request) frame to the second AP and receives anauthentication response (Authentication Response) frame sent by thesecond AP.

S2300: If the Authentication Response frame acknowledges that identityauthentication of the terminal equipment succeeds, the terminalequipment sends a reassociation request (ReAssociation Request) frame tothe second AP, and receives a reassociation response (ReAssociationResponse) frame sent by the second AP. If the ReAssociation Responseframe acknowledges that the second AP accepts an association request ofthe terminal equipment, the terminal equipment establishes anassociation with the second AP.

The ReAssociation Request frame includes an address realm of the firstAP. The address realm of the first AP carries a BSSID of the first AP.Therefore, on a network, a data packet sent to the first AP can beforwarded to the second AP according to the BSSID of the first AP, so asto reduce a packet loss during a process of handover between accesspoints.

Optionally, in S2300, the terminal equipment sends an associationrequest (Association Request) frame to the second AP, and receives anassociation response (Association Response) frame sent by the second AP.

S2400: The terminal equipment and the second AP jointly generate a keyby using the Extensible Authentication Protocol (“EAP” for short).

It should be noted that in S2200-S2400, the terminal equipment alwaysmaintains a TCP/IP connection with the first AP, an IP connection of anupper-layer application of a user is not disconnected, and it is ensuredthat an upper-layer application service of the user is not terminated.Therefore, during an entire process, the user does not perceive thehandover process, and when establishing the connection with the secondAP, the terminal equipment does not need to re-apply for an IP addressfrom the second AP, so that duration required by the handover process isreduced and user experience is improved.

Table 1 lists time required by each procedure and total time required byan entire handover process that are obtained when a method in the priorart is used for a handover between access points and when a method inthis embodiment of the present invention is used for a handover betweenaccess points. It should be noted that data shown in Table 1 is a resultof a single test, a distance between the terminal equipment and thedual-band radio access device when the test is being performed is lessthan 10 m, and there is no other interference in an environment.

TABLE 1 Sequence Prior art Present invention number Item (s) (s) 1Scanning 1.76 0.2  3 Authentication and 0.22 0.22 association 4 EPAauthentication 0.86 0.86 5 IP address assignment 1.58 — Total 4.42 1.28

It can be learned from Table 1 that the method for handover betweenaccess points according to this embodiment of the present invention canreduce interruption duration during a handover process, therebyimproving user experience.

The foregoing describes in detail the method for handover between accesspoints according to the embodiments of the present invention withreference to FIG. 2 to FIG. 3, and the following describes in detailterminal equipment according to an embodiment of the present inventionwith reference to FIG. 4. As shown in FIG. 4, terminal equipment 10includes: a processing unit 11, configured to: when the terminalequipment performs information transmission with a first access point APon a first frequency band, determine whether the terminal equipmentneeds to establish a connection with a second AP, where an operatingfrequency band of the second AP is a second frequency band, where theprocessing unit 11 is further configured to: when determining that theterminal equipment needs to establish the connection with the second AP,determine whether the first AP and the second AP are corresponding to asame dual-band radio access device; and a communications unit 12,configured to: when the processing unit 11 determines that the first APand the second AP are corresponding to the same dual-band radio accessdevice, send a connection request to the second AP when maintaining aprotocol layer connection with the first AP, where the connectionrequest is used to request to establish a connection with the second AP,where the communications unit 12 is further configured to: if receivinga success message that is fed back according to the connection requestand that is sent by the second AP, establish the connection with thesecond AP on the second frequency band.

Therefore, according to the terminal equipment in this embodiment of thepresent invention, when the first AP to which the terminal equipment iscurrently connected and the second AP to which the terminal equipmentexpects to be handed over are corresponding to the same dual-band radioaccess device, the terminal equipment establishes the connection withthe second AP when maintaining the protocol layer connection with thefirst AP. In this case, during a process of handing over terminalequipment to an access point, an IP connection of an upper-layerapplication of a user is not removed, so that the user does not perceivethe handover process. In addition, when the terminal equipmentestablishes the connection with the target AP, the target AP does notneed to assign an IP address to the terminal equipment, so as to reduceduration required by the handover process, thereby improving userexperience.

In this embodiment of the present invention, optionally, in the aspectof determining whether the first AP and the second AP are correspondingto a same dual-band radio access device, the processing unit 11 isspecifically configured to determine, according to a relationshipbetween a basic service set identifier BSSID of the first AP and a BSSIDof the second AP, whether the first AP and the second AP arecorresponding to the same dual-band radio access device, or determine,according to a relationship between a Media Access Control MAC addressof a default gateway of the first AP and a MAC address of a defaultgateway of the second AP, whether the first AP and the second AP arecorresponding to the same dual-band radio access device.

In this embodiment of the present invention, optionally, in the aspectof determining whether the terminal equipment needs to establish aconnection with a second AP, the processing unit 11 is specificallyconfigured to scan channels on the first frequency band and the secondfrequency band, and determine, according to a result of scanning thechannels on the first frequency band and the second frequency band,whether the terminal equipment needs to establish the connection withthe second AP.

In this embodiment of the present invention, optionally, in the aspectof scanning channels on the first frequency band and the secondfrequency band, the processing unit 11 is specifically configured toscan any channel of the channels on the first frequency band and thesecond frequency band, and when scanning of the any channel iscompleted, determine whether there is to-be-sent data. Thecommunications unit 12 is specifically configured to: when theprocessing unit 11 determines that there is to-be-sent data, send theto-be-sent data by using the first frequency band. The processing unit11 is specifically configured to: after the communications unit 12 sendsthe to-be-sent data by using the first frequency band, continue scanninganother channel of the channels on the first frequency band and thesecond frequency band.

In this embodiment of the present invention, optionally, the processingunit 11 is further configured to determine a first channel and a secondchannel, where the first channel is an operating channel of the first APon the first frequency band, and the second channel is an operatingchannel of the second AP on the second frequency band, and in the aspectof scanning channels on the first frequency band and the secondfrequency band, the processing unit 11 is specifically configured toscan the first channel and the second channel.

In this embodiment of the present invention, optionally, before theprocessing unit 11 determines whether the terminal equipment needs toestablish the connection with the second AP, the communications unit 12is further configured to store a first network configuration of thefirst AP and a second network configuration of the second AP, where thefirst network configuration includes the first channel, and the secondnetwork configuration includes the second channel; and in the aspect ofdetermining a first channel and a second channel, the processing unit 12is specifically configured to determine the first channel according tothe first network configuration, and determine the second channelaccording to the second network configuration.

In this embodiment of the present invention, optionally, in the aspectof sending a connection request to the first AP, the communications unit12 is specifically configured to send a reassociation request frame tothe second AP, where the reassociation request frame carries the basicservice set identifier BSSID of the first AP.

In this embodiment of the present invention, optionally, the firstfrequency band is 2.4 GHz, and the second frequency band is 5 GHz; orthe first frequency band is 5 GHz, and the second frequency band is 2.4GHz.

It should be understood that the terminal equipment 10 herein isembodied in a form of a functional unit. The term “unit” herein mayrefer to an application-specific integrated circuit (“ASIC” for short),an electronic circuit, a processor configured to execute one or moresoftware or firmware programs (for example, a shared processor, aproprietary processor, or a group processor) and a memory, a mergedlogic circuit, and/or another appropriate component that supports adescribed function. In an optional example, a person skilled in the artmay understand that the terminal equipment 10 may be configured toexecute each process and/or step in the method 1000 and the method 2000in the foregoing method embodiments. To avoid repetition, details arenot described herein again.

As shown in FIG. 5, an embodiment of the present invention furtherprovides terminal equipment 100. The terminal equipment 100 includes aprocessor 101, a memory 102, and a radio frequency (“RF” for short)circuit 103, where the RF circuit 103 may also be referred to as atransceiver. A person skilled in the art may understand that a structureof the terminal equipment shown in FIG. 5 does not constitute anylimitation on the terminal equipment. The terminal equipment may includecomponents more or fewer than those shown in the figure, or in theterminal equipment, some components are combined, some components aresplit, or the components are disposed differently.

The processor 101 is configured to: when the terminal equipment performsinformation transmission with a first access point AP on a firstfrequency band, determine whether the terminal equipment needs toestablish a connection with a second AP, where an operating frequencyband of the second AP is a second frequency band. The processor 101 isfurther configured to: when determining that the terminal equipmentneeds to establish the connection with the second AP, determine whetherthe first AP and the second AP are corresponding to a same dual-bandradio access device. If the processor 101 determines that the first APand the second AP are corresponding to the same dual-band radio accessdevice, the RF circuit 103 sends a connection request to the second APwhen maintaining a protocol layer connection with the first AP, wherethe connection request is used to request to establish a connection withthe second AP. If the RF circuit 103 receives a success message that isfed back according to the connection request and that is sent by thesecond AP, the processor 101 establishes the connection with the secondAP.

Therefore, according to the terminal equipment in this embodiment of thepresent invention, when the first AP to which the terminal equipment iscurrently connected and the second AP to which the terminal equipmentexpects to be handed over are corresponding to the same dual-band radioaccess device, the terminal equipment establishes the connection withthe second AP when maintaining the protocol layer connection with thefirst AP. In this case, during a process of handing over terminalequipment to an access point, an IP connection of an upper-layerapplication of a user is not removed, so that the user does not perceivethe handover process. In addition, when the terminal equipmentestablishes the connection with the target AP, the target AP does notneed to assign an IP address to the terminal equipment, so as to reduceduration required by the handover process, thereby improving userexperience.

It should be understood that, in this embodiment of the presentinvention, the processor 101 may be a central processing unit (“CPU” forshort), or the processor 101 may be another general purpose processor, adigital signal processor (DSP), an application-specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or anotherprogrammable logic device, a discrete gate or transistor logic device, adiscrete hardware assembly, or the like. The general purpose processormay be a microprocessor, or the processor may be any conventionalprocessor or the like.

The memory 102 may be configured to store a software program and amodule. The processor 101 runs the software program and the modulestored in the memory 102, so as to execute various function applicationsof the terminal equipment 100 and implement data processing. The memory102 may mainly include a program storage area and a data storage area.The program storage area may store an operating system, an applicationprogram required by at least one function (such as an audio playbackfunction and an image playback function), and the like. The data storagearea may store data (such as audio data and a phone book) that iscreated according to use of the terminal equipment 100, and the like. Inaddition, the memory 102 may include a high-speed random access memory,and may further include a nonvolatile memory, for example, at least onedisk storage device, a flash memory device, or another volatilesolid-state storage device.

The RF circuit 103 may be configured to receive and send information, orreceive and send a signal in a call process, and in particular, afterreceiving downlink information from a base station, send the informationto the processor 101 for processing, and in addition, send designeduplink data to the base station. Generally, the RF circuit 103 includesbut is not limited to an antenna, at least one amplifier, a transceiver,a coupler, a low noise amplifier (“LNA” for short), a duplexer, and thelike. In addition, the RF circuit 103 may further communicate with anetwork and another device by means of wireless communication. Anycommunications standard or protocol may be used for the wirelesscommunication, including but not limited to Global System for MobileCommunications (“GSM” for short), General Packet Radio Service (“GPRS”for short), a Code Division Multiple Access (“CDMA” for short) system, aWideband Code Division Multiple Access (“WCDMA” for short) system, aLong Term Evolution (“LTE” for short) system, an email, a short messageservice (“SMS” for short), and the like.

During an implementation process, the steps of the foregoing method maybe implemented by an integrated logic circuit of hardware in theprocessor 101 or by using an instruction in a form of software. Thesteps of the methods disclosed with reference to the embodiments of thepresent invention may be directly executed by a hardware processor, ormay be executed by a combination of hardware and a software module in aprocessor. The software module may be located in a storage medium thatis mature in the art, such as a random access memory, a flash memory, aread-only memory, a programmable read-only memory or an electricallyerasable programmable memory, or a register. The storage medium islocated in the memory 102, and the processor 101 reads information inthe memory 102 and completes the steps of the foregoing methods incombination with hardware of the processor 101. To avoid repetition,details are not described herein again.

Optionally, in an embodiment, in the aspect of determining whether thefirst AP and the second AP are corresponding to a same dual-band radioaccess device, the processor 101 is specifically configured todetermine, according to a relationship between a basic service setidentifier BSSID of the first AP and a BSSID of the second AP, whetherthe first AP and the second AP are corresponding to the same dual-bandradio access device; or determine, according to a relationship between aMedia Access Control MAC address of a default gateway of the first APand a MAC address of a default gateway of the second AP, whether thefirst AP and the second AP are corresponding to the same dual-band radioaccess device.

Optionally, in an embodiment, in the aspect of determining whether theterminal equipment needs to establish a connection with a second AP, theprocessor 101 is specifically configured to scan channels on the firstfrequency band and the second frequency band, and determine, accordingto a result of scanning the channels on the first frequency band and thesecond frequency band, whether the terminal equipment needs to establishthe connection with the second AP.

Optionally, in an embodiment, in the aspect of scanning channels on thefirst frequency band and the second frequency band, the processor 101 isspecifically configured to scan any channel of the channels on the firstfrequency band and the second frequency band, and when scanning of theany channel is completed, determine whether there is to-be-sent data.When the processor 101 determines that there is to-be-sent data, the RFcircuit 103 sends the to-be-sent data by using the first frequency band.After the RF circuit 103 sends the to-be-sent data by using the firstfrequency band, the processor 101 continues scanning another channel ofthe channels on the first frequency band and the second frequency band.

Optionally, in an embodiment, the processor 101 is further configured todetermine a first channel and a second channel, where the first channelis an operating channel of the first AP on the first frequency band, andthe second channel is an operating channel of the second AP on thesecond frequency band; and in the aspect of scanning channels on thefirst frequency band and the second frequency band, the processor 101 isspecifically configured to scan the first channel and the secondchannel.

Optionally, in an embodiment, before the processor 101 determineswhether the terminal equipment needs to establish the connection withthe second AP, the memory 102 is further configured to store a firstnetwork configuration of the first AP and a second network configurationof the second AP, where the first network configuration includes thefirst channel, and the second network configuration includes the secondchannel; and in the aspect of determining a first channel and a secondchannel, the processor 101 is specifically configured to determine thefirst channel according to the first network configuration, anddetermine the second channel according to the second networkconfiguration.

Optionally, in an embodiment, in the aspect of sending a connectionrequest to the second AP, the RF circuit 103 is specifically configuredto send a reassociation request frame to the second AP, where thereassociation request frame carries the BSSID of the first AP.

Optionally, in an embodiment, the first frequency band is 2.4 GHz, andthe second frequency band is 5 GHz; or the first frequency band is 5GHz, and the second frequency band is 2.4 GHz.

It should be understood that the terminal equipment 100 according tothis embodiment of the present invention may be corresponding to theterminal equipment 10 in the embodiment of the present invention, andmay be corresponding to the terminal equipment that executes the method1000 according to the embodiment of the present invention, and theforegoing and other operations and/or functions of each module in theterminal equipment 100 are intended to implement corresponding processesthat are corresponding to the terminal equipment in the methods in FIG.2 and FIG. 3. For brevity, details are not described herein again.

Therefore, according to the terminal equipment in this embodiment of thepresent invention, when the first AP to which the terminal equipment iscurrently connected and the second AP to which the terminal equipmentexpects to be handed over are corresponding to the same dual-band radioaccess device, the terminal equipment establishes the connection withthe second AP when maintaining the protocol layer connection with thefirst AP. In this case, during a process of handing over terminalequipment to an access point, an IP connection of an upper-layerapplication of a user is not removed, so that the user does not perceivethe handover process. In addition, when the terminal equipmentestablishes the connection with the target AP, the target AP does notneed to assign an IP address to the terminal equipment, so as to reduceduration required by the handover process, thereby improving userexperience.

A person of ordinary skill in the art may be aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm steps may be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of the present invention.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailed workingprocess of the foregoing system, apparatus, and unit, reference may bemade to a corresponding process in the foregoing method embodiments, anddetails are not described herein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected according toactual requirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of the presentinvention may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units are integratedinto one unit.

When the functions are implemented in the form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer readable storage medium. Based on such anunderstanding, the technical solutions of the present inventionessentially, or the part contributing to the prior art, or some of thetechnical solutions may be implemented in a form of a software product.The computer software product is stored in a storage medium, andincludes several instructions for instructing a computer device (whichmay be a personal computer, a server, a network device, or the like) toperform all or some of the steps of the methods described in theembodiments of the present invention. The foregoing storage mediumincludes: any medium that can store program code, such as a USB flashdrive, a removable hard disk, a read-only memory (ROM), a random accessmemory (RAM), a magnetic disk, or an optical disc.

The foregoing descriptions are merely specific implementations of thepresent invention, but are not intended to limit the protection scope ofthe present invention. Any variation or replacement readily figured outby a person skilled in the art within the technical scope disclosed inthe present invention shall fall within the protection scope of thepresent invention. Therefore, the protection scope of the presentinvention shall be subject to the protection scope of the claims.

1. A method for handover between access points, the method comprising: when terminal equipment performs information transmission with a first access point (AP) on a first frequency band, determining, by the terminal equipment, whether the terminal equipment needs to establish a connection with a second AP, wherein an operating frequency band of the second AP is a second frequency band; when the terminal equipment determines that the terminal equipment needs to establish the connection with the second AP, determining, by the terminal equipment, whether the first AP and the second AP are corresponding to a same dual-band radio access device; when the terminal equipment determines that the first AP and the second AP are corresponding to the same dual-band radio access device, sending, by the terminal equipment, a connection request to the second AP when maintaining a protocol layer connection with the first AP, wherein the connection request is used to request to establish a connection with the second AP; and when the terminal equipment receives a success message that is fed back according to the connection request and that is sent by the second AP, establishing, by the terminal equipment, the connection with the second AP.
 2. The method according to claim 1, wherein determining whether the first AP and the second AP correspond to the same dual-band radio access device comprises: determining, by the terminal equipment according to a relationship between a basic service set identifier BSSID of the first AP and a BSSID of the second AP, whether the first AP and the second AP are corresponding to the same dual-band radio access device.
 3. The method according to claim 1, wherein determining whether the terminal equipment needs to establish the connection with the second AP comprises: scanning, by the terminal equipment, channels on the first frequency band and the second frequency band; and determining, by the terminal equipment according to a result of scanning the channels on the first frequency band and the second frequency band, whether the terminal equipment needs to establish the connection with the second AP.
 4. The method according to claim 3, wherein scanning channels on the first frequency band and the second frequency band comprises: scanning, by the terminal equipment, any channel of the channels on the first frequency band and the second frequency band; when the terminal equipment completes scanning of the any channel, determining, by the terminal equipment, whether there is to-be-sent data; when the terminal equipment determines that there is to-be-sent data, sending, by the terminal equipment, the to-be-sent data by using the first frequency band; and after the terminal equipment sends the to-be-sent data by using the first frequency band, continuing scanning, by the terminal equipment, another channel of the channels on the first frequency band and the second frequency band.
 5. The method according to claim 3, wherein the method further comprises: determining, by the terminal equipment, a first channel and a second channel, wherein the first channel is an operating channel of the first AP on the first frequency band, and the second channel is an operating channel of the second AP on the second frequency band; and wherein scanning the channels on the first frequency band and the second frequency band comprises: scanning, by the terminal equipment, the first channel and the second channel.
 6. The method according to claim 5, wherein before determining whether the terminal equipment needs to establish the connection with the second AP, the method further comprises: storing, by the terminal equipment, a first network configuration of the first AP and a second network configuration of the second AP, wherein the first network configuration comprises the first channel, and the second network configuration comprises the second channel; and wherein determining the first channel and the second channel comprises: determining, by the terminal equipment, the first channel according to the first network configuration; and determining, by the terminal equipment, the second channel according to the second network configuration.
 7. The method according to claim 1, wherein sending the connection request comprises: sending a reassociation request frame to the second AP, wherein the reassociation request frame carries the BSSID of the first AP.
 8. The method according to claim 1, wherein the first frequency band is 2.4 GHz, and the second frequency band is 5 GHz; or wherein the first frequency band is 5 GHz, and the second frequency band is 2.4 GHz. 9.-16. (canceled)
 17. Terminal equipment comprising: a processor; a memory configured to store an instruction; and a transceiver, wherein the processor, the memory, and the transceiver are coupled to a bus system, wherein the transceiver is configured to receive and send messages under the control of the processor, to implement communication between the terminal equipment and an access point (AP); and the processor is configured to invoke the instruction stored in the memory, to execute steps: when terminal equipment performs information transmission with a first access point AP on a first frequency band, determining, by the terminal equipment, whether the terminal equipment needs to establish a connection with a second AP, wherein an operating frequency band of the second AP is a second frequency band; when the terminal equipment determines that the terminal equipment needs to establish the connection with the second AP, determining, by the terminal equipment, whether the first AP and the second AP are corresponding to a same dual-band radio access device; when the terminal equipment determines that the first AP and the second AP are corresponding to the same dual-band radio access device, sending, by the terminal equipment, a connection request to the second AP when maintaining a protocol layer connection with the first AP, wherein the connection request is used to request to establish a connection with the second AP; and when the terminal equipment receives a success message that is fed back according to the connection request and that is sent by the second AP, establishing, by the terminal equipment, the connection with the second AP.
 18. The terminal equipment according to claim 17, wherein the instruction for determining whether the first AP and the second AP correspond to the same dual-band radio access device, cause the processor to: determine, according to a relationship between a basic service set identifier BSSID of the first AP and a BSSID of the second AP, whether the first AP and the second AP are corresponding to the same dual-band radio access device.
 19. The terminal equipment according to claim 17, wherein the instruction for determining whether the first AP and the second AP correspond to the same dual-band radio access device, cause the processor to: determine, by the terminal equipment according to a relationship between a Media Access Control MAC address of a default gateway of the first AP and a MAC address of a default gateway of the second AP, whether the first AP and the second AP are corresponding to the same dual-band radio access device.
 20. The terminal equipment according to claim 17, wherein the instruction for determining whether the terminal equipment needs to establish the connection with the second AP, cause the processor to: instruct the terminal equipment to scan channels on the first frequency band and the second frequency band; and determine, by the terminal equipment according to a result of scanning the channels on the first frequency band and the second frequency band, whether the terminal equipment needs to establish the connection with the second AP.
 21. The terminal equipment according to claim 20, wherein the instruction for scanning channels on the first frequency band and the second frequency band, cause the processor to: instruct the terminal equipment to scan any channel of the channels on the first frequency band and the second frequency band; when the terminal equipment completes scanning of the any channel, determine whether there is to-be-sent data; when it is determined that there is to-be-sent data, cause the terminal equipment to send the to-be-sent data by using the first frequency band; and after the terminal equipment sends the to-be-sent data by using the first frequency band, instruct the terminal equipment to continue scanning another channel of the channels on the first frequency band and the second frequency band.
 22. The terminal equipment according to claim 20, wherein the instruction when invoked by the processor, cause the processor to determine a first channel and a second channel, wherein the first channel is an operating channel of the first AP on the first frequency band, and the second channel is an operating channel of the second AP on the second frequency band.
 23. The terminal equipment according to claim 22, wherein the instruction for scanning the channels on the first frequency band and the second frequency band, cause the processor to instruct the terminal equipment to scan the first channel and the second channel.
 24. The terminal equipment according to claim 22, wherein before determining whether the terminal equipment needs to establish the connection with the second AP, the instruction when invoked by the processor, cause the processor to instruct the terminal equipment to store a first network configuration of the first AP and a second network configuration of the second AP, wherein the first network configuration comprises the first channel, and the second network configuration comprises the second channel.
 25. The terminal equipment according to claim 24, wherein the instruction for determining the first channel and the second channel, cause the processor to determine the first channel according to the first network configuration; and determine the second channel according to the second network configuration.
 26. The terminal equipment according to claim 17, wherein the instruction for sending the connection request, cause the processor to send a reassociation request frame to the second AP, wherein the reassociation request frame carries the BSSID of the first AP.
 27. The terminal equipment according to claim 17, wherein the first frequency band is 2.4 GHz, and the second frequency band is 5 GHz, or wherein the first frequency band is 5 GHz, and the second frequency band is 2.4 GHz.
 28. The method according to claim 1, wherein determining whether the first AP and the second AP correspond to the same dual-band radio access device comprises: determining, by the terminal equipment according to a relationship between a Media Access Control MAC address of a default gateway of the first AP and a MAC address of a default gateway of the second AP, whether the first AP and the second AP are corresponding to the same dual-band radio access device. 